Nickel electroplating baths



a unit. MM

United States Patent 3,023,151 NICKEL ELECTROPLATING BATHS Wennemar Strauss, Dusseldorf-Holthausen, Gregor Michael, Dusseldorf, and Wolf-Dieter Willmund, Dusseldorf-Holthausen, Germany, assignors to Dehydag, Deutsciie Hydrierwerire G.m.b.H., Dusseldorf, Germany, a corporation of Germany No Drawing. Filed May 2, 1960, Ser. No. 25,843 Claims priority, application Germany May 6, 1959 14 Claims. (Cl. 204-49) 3,023,151 Patented Feb. 27, 1962 In this formula R and R stand for alkyl or aryl radicals, which may be identical or different from each other. Both of these radicals may carry substituents such as chlorine, bromine, hydroxyl groups, additional alkyl radicals and the like. Furthermore, the -CO-NH-SO group may also be present in the molecule several times. In this case, the general formula can be represented as by either of the following structural formulas wherein R and R are radicals as above defined and n is a whole number from 1' to 6.

nickel electroplating baths in addition to the above men tioned additives. However, it has often been observed that dull or hazy nickel electroplates are formed in the low currency density ranges (for example 0.25 to 0.5 ampere per square decimeter) or around perforations in the objects to be nickel-plated which are located Within these ranges, when baths are used which contain the above organic compounds.

It has been further noted that the degree of haziness depends upon the speed with which the objects move in the nickel bath. If substantial haziness Within a low current density range occurs at a movement rate of 20 centimeters per second, this haziness can be reduced by onehalf by reducing the movement rate to 10 centimeters per second, and at a movement rate of zero the haziness is completely suppressed. However, since in most cases the motion of the objects to be plated cannot be avoided in the operation of industrial electroplating baths, and moreover, since the rate of movement may be different from one situation to the other, the control of the electroplating baths from the point of view of the occurrence of dull or hazy zones with varying intensities is made much more difficult.

It is, therefore, an object of this invention to provide an electroplating process whereby bright, level and adherent nickel electro deposits may be obtained free from dull or hazy zones on said deposit over broad current density ranges regardless of the movement of the object to be plated in the electroplating bath.

Another object is to provide an additive for nickel plating baths from which bright, ductile and adherent nickel deposits uniform in color and free from dull and hazy zones may be obtained.

A further object is to provide an additive for nickel plating baths whereby movement of the object being electroplated does not result in hazy or dull zones on the electro deposit.

Yet another object is to provide an additive for a nickle plating bath which makes it possible to obtain full bright nickel electro deposits over a broad current density range.

These and other objects of our invention will become apparent as the description thereof proceeds.

We have now found that it is possible to avoid the occurrence of dull zones in low current density ranges, that is that the nickel electroplating process can be made independent of the rate of movement of the objects through the bath, by adding to the nickle baths N-sulfonylcarboxylic acid amides of the types The effect of the invention occurs upon use of the above products in the above mentioned known bath combinations as well as upon use of these products alone or in combination with known leveling agents.

Examples of agents of the type used in accordance with the invention are: N: (benzenesulfonyl) -benzoylamide N= benzenesulfonyl) -p-toluylamide CH C H CONH-SO C H N- (p-toluenesulfonyl -p-toluylamide v N-(octylsulfonyl)-acetamide CH CONH4O C H N-(benzenesulfonyl)-2-ethyl-hexanoic acid amide C H CONHSO C H N- 3 ,4-dichlorb enzenesulfonyl) -p -toluyl amide SO C H CH N,N'-bis(xylenesulfonyl)-adipic acid-diamide In addition to the above, similar compounds prepared from polycarboxylic acids such as citric acid, terephthalic acid, trimesic acid, pyromellitic acid, benzene pentacarboxylic acid, mellitic acid and the like.

The amount of the additive used in the bath is from 0.1 to 5.0 g./l.

Particularly good brightening and leveling effects are achieved when the above described agents are combined with salt-like reaction products of tertiary monoand poly-nuclear heterocyclic nitrogen bases of the aromatic type and sultones, such as with the internal salt of pyridinium-N-propane-w-sulfonic acid, or similar compounds of this type. For the purpose of suppression of pore formation, the baths may also be modified with small amounts of halogen-alkane-sulfonic acids, such as 3- chloro-Z-hydroxypropane-sulfonic acid, 2-bromo-ethane-l sulfonic acid or other compounds of this .type or their salts, as well as with known wetting agents.

The simplest and most readily accessible of the above named saltlike reaction products is the internal salt of pyridinium-N-propane-w-sulfonic acid having the follow ing structural formula:

which may be obtained, for example, by a reaction of pyridine with 1,3-propanesultone under the conditions set forth by Helberger. However, other analogous internal sulfonic acid salts may also be used in place of the above pyridinium salt, for example those in which the heterocyclic ring system is a C-substituted pyridine radical, such as a picoline, lutidine, ethylpyridine radical, and the like. Similarly, those analogous compounds which contain a polycyclic heterocyclic radical in place of the pyridine or substituted pyridine radical, such as a quinoline, isoquinoline, quinaldine, lepidine, acridine, phenanthridine radical, and the like, may also be used as modifiers of nickel electroplating baths in accordance with the present invention. Finally, also those internal sulfonic acid salts of the above general class, wherein the pyridine ring is replaced by a heterocyclic radical comprising more than one nitrogen atom in the ring, have been found to be effective additives for nickel electroplating baths, such as the internal sulfonic acid salts of pyridazine, pyrimidine, pyrazine, phthalazine, quinazoline, quinoxaline, phenazine, and the like. In this last group of compounds the other nitrogen atoms in the heterocyclic ring system may also be linked to additional internal alkylsulfonic acid radicals of the type shown in the structural formula above. Moreover, any of the heterocyclic radicals recited herein may carry substituents such as halogen, nitro-groups, and the like.

In addition to 1,3-propanesultone or 1,3- and 1,4- butanesultone, other sultones may be used to produce the above-described class of additives for nickel electroplating baths. For example, substituted sultones such as 1,1-dimethy1-1,3-propanesultone (isopentanesultone) may be reacted with the various types of heterocyclic compounds above described to produce internal salts of quaternary ammonium N dimethyl-propane-w-sulfonic acid. Such compounds are also effective additives for nickel electroplating baths. Finally, internal sulfonic acid salts of heterocyclic compounds which have been analogously formed from cycloaliphatic sultones such as tolylsultone, 1,8-naphthalenesultone, and the like, may also be used for the purpose herein set forth.

In other words compounds having the general structural formula 1 \N/ \SO2 wherein R is a cyclic radical which includes the nitrogen atom and has carbon atoms or carbon and additional nitrogen atoms in the ring, and R is a lower aliphatic, cycloaliphatic or aromatic radical, are elfective additives for nickel electroplating baths which will produce a marked improvement in-the brightness and smoothness of the nickel electrodeposits.

In practice, the compounds herein described are added to the nickel electroplating bath either as such, that is in the form of the internal salt, or also in the form of the corresponding metal sulfonates produced by reacting the internal salt with a suitable inorganic metal base,

whereby the cyclic sulfonic radical is cleaved to produce the compound better understand and practice the invention and are not intended to be limitative.

Example I A Watts-type nickel electroplating bath was modified with 1.5 grams per liter N-(benzenesulfonyl)-benzoylamide, 0.35 g./l. of the internal salt of pyridinium N-propane-w-sulfonic acid and 1 g./l. of the sodium salt of 3-chloro-2-hydroxypropanesulfonic acid, full bright nickel electroplates were obtained within a current density range of 0.1 to 8 amperes per square decimeter at 55 C. Even at a movement rate of 20 centimeters per second, the formation of a dull zone in the low current density range was not observed. However, when N-(benzenesulfonyl) -benzoy1amide was replaced by the sodium salt of toluenesulfamide in the above process, substantial dull areas are formed in the low current density range 0.2-0.5 amp./dm. at movement rates of 3.8 to 20 centimeters per second.

Example II A nickel electroplating bath was modified with 1.0 gram per liter N-(benzenesulfonyl)-paratoluylamide, 0.8 gram per liter of the inner salt of quinolinium-N-propane-w-sulfonic acid, 1.2 gram per liter of the sodium salt of w-hydroxypropane-sulfonic acid and 0.5 g./l. sodium octylsulfate. This bath produced satisfactory bright nickel electro deposits at 50 centigrade in a current density range of 0.1 to 8 amperes per square decimeter. When, instead of the N-(benzenesulfonyl)-para-toluylamide, 1.5 g./l. benzoic acid-4-sulfonamide was used, dull zones occurred in lower density ranges of 0.2-0.5 amp./dm. especially at the edges of drill holes through the objects being plated.

While we have set forth certain specific examples and preferred modes of practice of our invention, it will be understood that the invention is not limited thereto, and that various changes and modifications may be made in our invention without departing from the spirit of the disclosure and the scope of the appended claims.

We claim:

1. A Watts-type nickel electroplating bath for obtaining nickel electrodeposits free from dull and hazy areas having dissolved therein an N-sulfonyl carboxylic acid amide compound having a structural formula selected from the group of consisting of:

and

wherein R and R' are selected from the group consisting of alkyl and aryl radicals, and n is a whole number from 1 to6 said N-sulfonyl carboxylic acid amide being present in sufiicicnt amount to obtain said electrodeposits free from dull and hazy areas.

2. A Watts-type nickel electroplating bath for obtaining nickel electrodeposits free from dull and hazy areas having dissolved therein an N-sulfonyl carboxylic acid and In wherein R and R are selected from the group consisting of alkyl and aryl radicals, and n is a Whole number from 1 to 6, in an amount from 0.1 to 5.0 g./l.

3. The bath of claim 2 wherein the electroplating bath contains in addition from about 0.1 to 10 g./l. of salt-like reaction products of tertiary monoand poly-nuclear aromatic heterocyclic nitrogen bases and sultones.

4. The bath of claim 2 wherein the electroplating bath contains in addition haloalkane sulfonic acids and their salts.

5. The bath of claim 2 wherein the electroplating bath contains in addition wetting agents.

6. A Watts-type nickel electroplating bath having dissolved therein from about 0.1 to about g./l. of N-(benzene-sulfonyl)benzoylamide, the internal salt of pyridinium-N-propane-w-sulfonic acid and the sodium salt of 3- chloro-2-hydroxypropane sulfonic acid.

7. A Watts-type nickel electroplating bath having dissolved therein from about 0.1 to about 5 g./l. of N-(benzenesulfonyl)-paratoluylamide, the inner salt of quinolinium-N-propane-w-sulfonic acid, the sodium salt of whydroxypropane-sulfonic acid, and sodium octyl sulfate.

8. The method of producing bright and smooth nickel electrodeposits free of dull and hazy areas on metal objects irrespective of movement of said object and under broad current density ranges, which comprises electroplating said objects in a Watts-type nickel bath having dissolved therein an N-sulfonyl carboxylic acid amide compound having a structural formula selected from the group consisting of:

wherein R and R are selected from the group consisting of alkyl and aryl radicals, and n is a whole number from 1 to 6, said N-sulfonyl carboxylic acid amide being present in suflicient amount to obtain said electrodeposits free from dull and hazy areas.

9. The method of producing bright and smooth nickel electrodeposits free of dull and hazy areas on metal objects irrespective of movement of said object and under broad current density ranges, which comprises electroplating said objects in a Watts-type nickel bath having dissolved therein an N-sulfonyl carboxylic acid amide compound having a structural formula selected from the group consisting of:

and

wherein R and R are selected from the group consisting of alkyl and aryl radicals, and n is a whole number from 1 to 6, in an amount from 0.1 to 5.0 g./l.

10. The method of producing bright and smooth nickel electrodeposits free of dull and hazy areas on metal objects irrespective of movement of said object and under broad current density ranges, which comprises electroplating said objects in a Watts-type nickel bath as in claim 9 having dissolved therein from about 0.1 to 10 g./1. of salt-like reaction products of tertiary monoand polynuclear aromatic heterocyclic nitrogen bases and sultones.

11. The method of producing bright and smooth nickel electrodeposits free of dull and hazy areas on metal objects irrespective of movement of said object and under broad current density ranges, which comprises electroplating said objects in a Watts-type nickel bath as in claim 9 having dissolved therein haloalkane sulfonic acids and their salts.

12. The method of producing bright and smooth nickel electrodeposits free of dull and hazy areas on metal objects irrespective of movement of said object and under broad current density ranges, which comprises electroplating said objects in a Watts-type nickel bath as in claim 9 having dissolved therein wetting agents.

13. The method of producing bright and smooth nickel electrodeposits free of dull and hazy areas on metal objects irrespective of movement of said object and under broad current density ranges, which comprises electroplating said objects in a Watts-type nickel bath having dissolved therein -from about 0.1 to about 5 g./l. of N-(benzene-sulfonyl)benzoylamide, the internal salt of pyridinium N-propane-w-sulfonic acid and the sodium salt of 3- chloro-Z-hydroxypropane sulfonic acid.

14. The method of producing bright and smooth nickel electrodeposits free of dull and hazy areas on metal objects irrespective of movement of said object and under broad current density ranges, which comprises electroplating said objects in a Watts-type nickel bath having dissolved therein from about 0.1 to about 5 g./l. of N- (benzenesulfonyl)-paratoluylamide, the inner salt of quinolinium-N-propane-w-sulfonic acid, the sodium salt of w-hydroxypropane-sulfonic acid, and sodium octyl sulfate.

No references cited. 

1. A WATTS-TYPE NICKEL ELECTROPLATING BATH FOR OBTAINING NICKEL ELECTRODEPOSITS FREE FROM DULL AND HAZY AREAS HAVING DISSOLVED THEREIN AN N-SULFONYL CARBOXYLIC ACID AMIDE COMPOUND HAVING A STRUCTURAL FORMULA SELECTED FROM THE GROUP OF CONSISTING OF: 